There are so many caveats in the price-matching fine print that it’s easy to be misled. That’s why I’ve decided to give you a consumer’s guide to these programs, so you know how to work around the conditions and caveats set by retailers and e-tailers.

What Trips Up Shoppers

“Price-matching policies today come with complicated requirements and exclusions that could trip up even the savviest of shoppers,” says Edgar Dworsky, founder of ConsumerWorld.org, a shopper advocacy site based in Somerville, Mass.

Some retailers restrict price matches to only certain competitors. Best Buy, for example, will match prices against local rivals and 20 sites, including Amazon and Apple, but not at popular sites like Abt Electronics or jr.com.

Similarly, Staples.com will match prices with only 14 online retailers, including Office Depot and Office Max. It will not, however, match buy.com, which often sells comparable items for less than Staples does.

Lowe’s will offer 10 percent off a rival’s lower price, but only if the item is available at an actual store, not a website.

Many retailers limit which products they’ll match. Amazon offers price matching only on televisions and only at certain sites, like bestbuy.com, bhphotovideo.com and walmart.com. Toys R Us has said it will match online prices for baby gear only at “selected national competitors,” but hasn’t named them. (You’ll probably have to ask your local store manager; the chain’s site says its program “may vary by store.”)

Sales and promotional items are often excluded. Sears won’t match a competitor's “doorbuster” prices, those highly discounted items some stores use to lure shoppers. Amazon, Toys R Us, Paypal and others are excluding Black Friday and Cyber Monday deals from their price matching.

After a purchase, the amount of time you have to claim a price match differs dramatically from chain to chain. At Best Buy, you can get a retroactive discount if you spot a lower price within 30 days of buying the item. But Staples gives you only 14 days; Toys R Us, just seven days.

Getting the lower price can take effort. Most stores offering price matches require proof of the lower price from a newspaper ad or website link. So if you’re trying to get your discount from an online retailer, you probably won’t be able to do so over the Internet.

At Staples.com, for example, you must call to provide the link where you found the lower price. “It has to be the same exact item — model number and color — and we have to make sure that store has it in stock,” a Staples representative told me. The entire process may take two to three minutes per item.

PayPal promises to give customers cash back if they discover, within 30 days of purchase, a lower price on any product they bought through their PayPal account before Dec. 31 (maximum refund: $250 per item and no more than $1,000 total). But to get your price-guarantee savings, you must fill in a PayPal refund form and attach receipts as well as proof of the ad or website screenshot.

Stores have been inundated by customers who visit them to see, touch and test items, but then leave to buy them online, where prices are often lower. (In the business, that’s called “showrooming.”) So they’re pushing price matching as a way to lure you inside — and more important, inspire you to buy there.

4 Price-Matching Tips

To make the most of this season’s holiday price-matching guarantees, Dworsky offers these four tips:

1. Be prepared to argue your case. “Despite their stated policies, some stores will balk at doing price matches,” he says. So be sure you have a copy of the store’s policy from its ad or site and proof of the rival’s lower price.

2. Ask for a price match even at stores that don’t offer formal guarantees. “The savvy shopper can often negotiate a lower price merely by citing a competitor’s current price,” Dworsky says.

3. After you’ve bought an item, keep your eyes on the price charged by competitors. “You need to shop around after making a purchase,” Dworsky says. If the store where you made the purchase has a retroactive price match program and you see that a rival's price has dropped, go back and ask for a refund.

4. Don’t overlook your credit card for a possible price match. Several cards, including ones from Chase and Citigroup, offer price guarantees as one of their benefits.

Cardratings.com founder Curtis Arnold notes that in addition to the shopping rewards it offers, the Chase Sapphire Preferred Benefits card will refund the difference between the price you paid for an eligible item and a “subsequent covered lower advertised price” for the same item within 90 days of purchase.

Caroline Mayer is a consumer reporter who spent 25 years working for The Washington Post, covering such issues as product safety, scams, and credit cards. Mayer has received several awards, including the Betty Furness Consumer Media Service Award. She has written for Consumer Reports, CBS MoneyWatch, Ladies Home Journal, Kaiser Health News and others. Follow her on Twitter @consumermayer@consumermayer